On Fri, 16 Sep 2016 11:25:54 +0200
Christoph Lauber <christ...@midsommar.ch> wrote:

> Hi H
> 
> Are you sure you really need the "Offset" field for your aims?
> Don't you need just the "Time frame size"? There you can choose "step 
> width" like minutes, days, month, years...
> 
> The offset should be a feature, you can time which style to display 
> when. But I think this is not what you want to do.
> 
> Regards
> Christoph
> 
Hi Christoph,

Thanks for the response.
I will take two steps back and explain what I am trying to accomplish
rather than where I am having trouble.

I have been a professional C/C++ developer, but have never used Python.
(I could learn to write python scripts if required, but they are not
obvious to me - yet)

I have road crash data where, for each road crash, I have a field for
date and a different field for time.  (The data came as csv, I put it
into postgis, but for Time Manager have saved it to a shp file)

The data is updated every couple of months, and starts in 2001.

When looking at road crash data I generally consider crashes in 5 year
groupings. I am wanting to use Time Manager to show the 5 year
groupings, annually.
(There are times I may want to change the length of the groupings, so I
want something where I can easily change from 5 years.  I am currently
dealing only with calender years) 

Using the 5 year groupings, this is I want from Time Manager:

Frame 1 - road crashes 2001 to 2005
Frame 2 - road crashes 2002 to 2006
Frame 3 - road crashes 2003 to 2007
...
Frame 12 - road crashes 2012 to 2016

My understanding is that for this the Time Frame Size is 'one year' as
that is the interval between each frame.  (Correct me if I am wrong)

I have seen a number of sample files, and my intent was to create
5 copies of the data, and offset them to cover a 5 year period in each
(annual) frame.


To make the situation more challenging, I am also thinking of doing a
heatmap rather than just showing individual points.  I do not think I
can create a heatmap using multiple layers.


My fall back solution is that I create a new table / layer that contains
the primary key from my crashes table, the coordinates of the crash and
a year in which to display it.  Because each crash is being displayed in
5 different years, this table would have 5 entries for each crash,
but Time Manager would step through a heatmap for each
year.  

I was hoping I would not need to create a new table.

Thanks again!
H








> > -----Urspr√ľngliche Nachricht-----
> > Von: h [mailto:hdi...@bigpond.net.au]
> > Gesendet: Dienstag, 13. September 2016 14:08
> > An: qgis-user <Qgis-user@lists.osgeo.org>
> > Betreff: [Qgis-user] "Time Manager" - Offset units
> >
> > I have a couple of questions about the "Time Manager" plugin -
> > firstly Is this the right place for me to post them to?
> > This is the first of a couple of questions I have, so please
> > redirect me to the correct place if this is not it.
> >
> > My first question is concerning the "Offset" field when adding
> > layers. I have a dataset I want to step through in years showing
> > data for current year and previous year.
> > I can do this, by setting the offset for the 'previous' year as
> > 32000000.  I am guessing that the offset is in seconds (there are
> > about 32 million seconds in a year)
> >
> > *  Is my guess correct that the offset is in seconds?
> > *  Can I change the unit of the offset (I would like to use years)?
> > *  If the offset can only be entered in seconds, I will improve my
> > approximation of 32 million seconds, but what do I do about leap
> > years?
> >
> > Many thanks,
> > H
> >
> >
> 

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